1. Field of the Invention
The present invention relates to a liquid electrophotographic image forming apparatus having a waste developing agent container and, more particularly, to a liquid image forming apparatus having a waste developing agent container holding a waste developing agent from a photosensitive body provided in a developing container.
2. Description of the Related Art
In general, electrophotographic image forming apparatuses form an electrostatic latent image on a photosensitive medium, such as a photosensitive drum or a photosensitive belt, develop the electrostatic latent image by a developing agent of a predetermined color, and transfer the developed image onto a sheet of paper, thereby forming a desired image.
Such electrophotographic image forming apparatuses are classified into a dry type and a wet type according to the type of developing agent. Dry type image forming apparatuses use a powder state of toner, while liquid image forming apparatuses use a liquid developing agent, in which the toner is mixed with a liquid carrier. The liquid image forming apparatuses have better printing quality than the dry type image forming apparatuses and reduce risks of health problems caused by harmful toner dust.
FIG. 1 schematically shows the structure of a conventional liquid color image forming apparatus. FIG. 2 shows a detailed diagram of an image forming unit of FIG. 1 and illustrates a magenta image forming unit M among image forming units having the same structure of FIG. 1.
Referring to FIGS. 1 and 2, a plurality of image forming units are arranged serially on a circulation route of a transfer belt 40, which moves on an endless track by a plurality of rollers 41, 42, and 44. Each of the image forming units transfers cyan (C), magenta (M), yellow (Y), and black (K) images, respectively, onto the transfer belt 40. Each image forming unit includes a photosensitive drum 30, which transfers a toner image of a predetermined color onto the transfer belt 40; a charger 36, which charges the surface of the photosensitive drum 30 at a predetermined electric potential; a laser scanning unit (LSU) 38, which forms an electrostatic latent image by radiating light onto the charged surface of the photosensitive drum 30; a developing unit 10, which develops the electrostatic latent image into a predetermined toner image; and a cleaning blade 31, which removes a developing agent remaining on the photosensitive drum 30 after the developed toner image is transferred onto the transfer belt 40. A waste developing agent removed by the cleaning blade 31 from the photosensitive drum 30 is collected in a waste developing agent tub 32 provided under the cleaning blade 31 and is then brought to and stored in a waste developing agent container 34 via a guide pipe 33 connected to the lower part of the waste developing agent tub 32. Reference numeral 35 denotes an eraser that erases an electric potential on the photosensitive drum 30.
When the transfer belt 40 is supported and rotated by a driving roller 41, a second transfer backup roller 44, and a plurality of first transfer backup rollers 42 corresponding to the photosensitive drum 30, the image that is formed on the photosensitive drum 30 is transferred onto the transfer belt 40. A second transfer roller 43 is installed to rotate in a direction opposite to the rotation of the second transfer backup roller 44, and the transfer belt 40 is placed between the second transfer backup roller 44 and the second transfer roller 43. The second transfer roller 43 transfers the image on the transfer belt 40 onto a sheet of paper 60.
The paper 60, onto which the color image is transferred by the second transfer roller 43, is heated at a predetermined temperature and pressurized by a fusing unit 50 installed on a paper exhaust route, and the toner image is fixed on the paper 60.
The developing unit 10 includes a developing container 14 in which the developing agent (D) is stored; a developing roller 15 of which a portion is dipped in the developing agent (D) and installed to face the photosensitive drum 30; a depositing roller 16; a cleaning roller 17; and a metering roller 18.
Part of the developing roller 15 is dipped in the developing agent (D) stored in the developing container 14. The depositing roller 16 is dipped in the developing agent (D) stored in the developing container 14, and a predetermined voltage is applied to the depositing roller 16 being spaced apart from the developing roller 15 by a predetermined gap. The depositing roller 16 sticks the developing agent (D) onto the surface of the developing roller 15 utilizing a difference in electric potential between the depositing roller 16 and the developing roller 15 having the predetermined voltage.
The metering roller 18 is installed to be adjacent to the developing roller 15 and regulates the developing agent stuck on the developing roller 15 to a predetermined thickness.
The cleaning roller 17 cleans the developing agent (D) remaining on the surface of the developing roller 15 after the developing roller 15 has developed the electrostatic latent image on the photosensitive drum 30.
However, an image forming apparatus having the above structure must separately include a container in which a waste developing agent is stored outside of the developing container, and thus the space within the image forming apparatus should be increased.